Fault-tolerant magnetic bearing control system architecture

Abstract

A fault-tolerant control system for a magnetic bearing arrangement which maximizes dynamic response of the control system is disclosed. The arrangement includes a main digital signal processor responsive to rotor position/velocity signals to supply control signals to bearing control coils and a secondary digital signal processor responsive to accelerometer signals to provide open-loop vibration control for correction of mass imbalance of the rotor system. In addition, sources of vibration which have fundamental frequencies at some multiple of the rotor system rotational frequency can also be controlled.

I claim: 
     
       1. A method for correcting imbalance in a rotor device having magnetic bearings comprising: providing a bearing arrangement comprising control means including closed loop rotor position means comprising a first signal processing means and separate open loop vibration correction means comprising a second signal processing means which generates an open loop perturbation signal and vibration sensing means for detecting when vibration of a stationary portion of the bearing arrangement exceeds a predetermined level wherein the closed loop rotor position means includes one enabled closed-loop rotor position controller means and one disabled closed-loop rotor position controller means;   providing at least two independent position sensor means dedicated to each of the enabled closed-loop rotor position controller means and one disabled closed-loop rotor position controller means for each axis along which the axial position of the rotating members is controlled; and   simultaneously enabling the disabled closed-loop rotor position controller means and disabling the enabled closed-loop rotor position controller means with the open loop vibration correction means when vibration of a stationary portion of the bearing arrangement exceeds a predetermined level.   
     
     
       2. A method for correcting imbalance in a rotor device having magnetic bearings in accordance with claim 1 further comprising providing input signals from each enabled closed-loop rotor position controller means to at least two independent power amplification means associated with each axis of the bearing arrangement and providing control current from each power amplification means to a dedicated control coil therefor, wherein the control coil links a common flux path associated with a given bearing axis along which rotor position is controlled.